isobutylene is one of the important chemical raw materials that are converted into ethyl tert-butyl ether (ETBE), paraxylene, and a methyl methacrylate (MMA) monomer. Among these, for example, the MMA monomer is a substance with significantly high utility value as a raw material for poly(methyl methacrylate) that is useful as a transparent resin. There is a method, as one of the methods for producing the MMA monomer, to synthesize this MMA monomer by using isobutylene as a starting material.
Isobutylene as a raw material for the MMA monomer is obtained by extracting isobutylene as tert-butanol from the spent BB that is a residue obtained by the fractional distillation of butadiene from the C4 fraction obtained by naphtha cracking by the hydration reaction using an acid catalyst and dehydrating this. In addition, there is also a method in which methyl tert-butyl ether is once synthesized from isobutylene in the spent BB and methanol and is then decomposed. Such a current method for producing isobutylene uses petroleum as a raw material. Hence, the development of a novel method which does not depend on petroleum is desired in the recent situation that the depletion of petroleum is concerned.
In addition, carbon dioxide generated when petroleum is burned is regarded as a cause of global warming. Thus, the biorefinery technology has attracted the worldwide attention as an energy and chemical producing technology from biomass of a renewable resource. The biorefinery is a technology to produce synthesis gas, saccharides such as glucose, and aromatic compounds such as lignin by the gasification, saccharification, and extraction of various kinds of biomass and to produce energy and chemicals by converting them in various ways. Examples of the product that is produced by the biorefinery may include ethanol, butanol, or diesel oil as energy. In chemicals, it is possible to produce a significantly great number of chemicals by the derivation from key compounds (platform compounds) such as saccharide-derived succinic acid, 3-hydroxypropionic acid, and aspartic acid proposed by the US Department of Energy.
Meanwhile, isobutanol is also known to be produced by fermenting glucose and mentioned as one of the biomass-derived raw materials. It is described in, for example, Patent Literature 1, Patent Literature 2, Patent Literature 3, Patent Literature 4, Patent Literature 5, and Non-Patent Literature 1 that isobutylene can be produced by dehydrating isobutanol.